The Argentine government has received logistical help from several governments, including Britain, Chile and the United States.
"We received seven satellite calls that likely came from the submarine San Juan".
However, the navy was unable to confirm that those calls originated from the submarine.
Navy spokesman Enrique Balbi says Monday that a USA aircraft was sent to check an area where the noise was heard by two Argentine Navy ships.
On Sunday spokesman Enrique Balbi announced that harsh weather conditions had hampered the search.
Recent bad weather in the region has made the search more hard for aircraft and ships; the Patagonia Coast is known for bad storms.
There is a feeling of "cautious enthusiasm", naval expert Fernando Morales told C5N television.
Another submarine, the Salta, the same as the San Juan is docked in the base.
The submarine disappeared last Wednesday along the country's Atlantic coast with 44 crewmen on board. "This is why we are deploying all resources with high-tech sensors". The craft was navigating normally, underwater, at a speed of five knots toward Mar del Plata when it was last heard from, he said.
At the entrance to the Mar del Plata base, locals hung signs with messages in support of the crew members and their families on a chain-link fence.
They were joined by President Mauricio Macri, who arrived late morning but did not address the media. "Thank God", he said.
She graduated from Argentina's submarine and diving school in 2012 as the first female officer and always loved her job working at sea, according to her sister Silvina Krawczyk.
The navy has not ruled out any hypothesis.
The navy said an electrical outage on the diesel-electric-propelled vessel may have downed its communications, though protocol calls for submarines to surface if communication is lost.
Al Jazeera's Daniel Schweimler reports from the submarine's base in Mar del Plata.
A US Navy P-8A Poseidon plane was immediately dispatched to the site where the noises were detected by two Argentine ships. Previously, the modern diesel-electric sub, built in 1983 and put into service in 1985, went through a mid-life overhaul, completed in 2013.
It underwent a refit between 2007 and 2014 to extend its use by about 30 years.
The UK is also deploying the Royal Navy's specialist Submarine Parachute Assistance Group to assist with the search efforts, and the Falklands Islands patrol vessel HMS Clyde is returning from a patrol to South Georgia in order to assist with the search.